Dear responsible person
Is it correct to start an official letter from the words shown above if you don't know a persons gender and its position at the company?

Question

Answer

No you would not start a letter in this way.
This is correct:
Dear Sir/Madam,

Answer

"Dear responsible person" sounds very impersonal and even comical. It either sounds sarcastic, or you're suggesting that the reader's colleagues are irresponsible. :)  Leigh's answer is exactly what you need.

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